Embodiments of the present disclosure relate to the field of communication systems and headset technology, and specifically related to systems utilizing a human body for communication, headsets using a human body as a transmission medium and methods thereof.
With the continuous development of society, people's demand for wearable electronic products (such as headphones, watches, hand rings, etc.) is increasing. Comparing with the traditional way of wired transmission signal, wireless transmission greatly improves the convenience and comfort of wearable electronic products. At present, for a real wireless headset with stereo, audio transmission between left and right ears is achieved mainly through a pair of Bluetooth headphones or through NFMI (near field magnetic induction technology) forwarding.
The 2.4G frequency band used by Bluetooth has large interference. The electromagnetic waves of this frequency band can be easily absorbed by a human body, making it difficult to achieve stable transmission. While NFMI uses inductance and capacitance resonance mode to achieve high impedance, the bandwidth of which is narrower (a typical central frequency being 10-30 MHz, 3 dB bandwidth being 0.1-3 MHz). Therefore, the transfer rate between the ears when using these two methods is low, and high-quality wireless stereo headphones cannot be achieved. In addition, headphones using NFMI forwarding need an additional integrated inductor coil to achieve magnetic coupling, usually a winding ferrite core inductor coil, having a typical size of 6×3×2 mm3, and a relatively large antenna size; thus, the design of the headphones is greatly limited, not conducive to the miniaturization of real wireless headphones.
In order to avoid human magnetic field interference to the signal transmission between the left and right Bluetooth earphones, improve the reliability of transmission, the existing technology integrates human electrodes in the Bluetooth headset, with the help of the human body for communication.
However, in order to achieve human body communication, the human electrode is usually used as an antenna. The output signal of the transmitter is loaded to the human body through an electrode in contact with the human body, the signal is transmitted through the human body, and the receiver of another communication device receives the signal through an electrode in contact with the human body. Since the high frequency noise on the human body can easily be coupled into the receiver by capacitance coupling, which affects the signal-to-noise ratio of input signals of the receiver. As far as the current technology is concerned, in order to increase the signal-to-noise ratio of the input signals of the receiver, the only solution is to increase the area of the human electrode, but this will inevitably cause the overall shape of the headset to be larger, which is not conducive to the miniaturization of headphones.